1. Field of the Invention
The present invention relates to an optical switching device for externally switching in an apparatus housed in a water-proof case.
2. Related Background Art
In a prior art apparatus to be used in water, a switch for a power supply of the apparatus or for switching functions is constructed in a water-proof structure by forming a hole in a water-proof case, passing a switch shaft therethrough and arranging a water-proof O-ring at an engagement of the switch shaft and the hole, and rotating the switch shaft, or by arranging a reed switch or a leaf spring in the water-proof case and externally actuating the switch by a magnet.
However, the method of forming the hole in the water-proof case and rotating the switch shaft needs many parts for the water-proof around the shaft, is expensive, and is apt to cause the break of water tight and the leakage of water because the switch shaft water-tighted by the 0-ring moves in the hole formed in the case. In the method of externally actuating the reed switch or the leaf spring in the water-proof case by the magnet, the leakage of water can be avoided because of no through-hole but iron sand which is magnetic material deposits on the magnet, which leads to inoperation of the switch.